There has been much talk in US defence circles about the threat of cyberwarfare. That is understandable given that no country is as reliant on computers and, therefore, as vulnerable to attack. Rules on dealing with strikes will be approved soon, although they will be highly classified. Wrongly, just as with the US' use of drones, all indications are that the policy will be again underpinned by a strategy of pre-emption. As with drones, there should be international guidelines and controls on what is and is not permissible.

Officials have suggested the threat of an attack as being akin to war. President Barack Obama announced in his state-of-the-union address that he had signed an executive order putting in place measures to prevent America's enemies from sabotaging infrastructure, like power grids and financial institutions. Defence Secretary Leon Panetta has referred to a "cyber-Pearl Harbour" and others have warned it is only a matter of time before there is a strike that would "make 9-11 look like a tea party". There have yet to be proven deaths attributed to cyberweapons like viruses and worms, but the crashing of websites in Estonia in 2007, and Georgia the following year, and the taking out in 2010 of centrifuges Iran was using to enrich uranium shows what havoc can be wrought.

But an attack on the internet is not the same as one from land, sea or air. While governments can be behind them, the nature of cyberspace means that identities can be hidden and suspicions difficult to prove. That makes defence and offence shadowy and secretive, a place lacking rules and guidelines. The result is fear, uncertainty and instability.

At the heart of the US strategy is its Cyber Command, set up to defend networks and produce weapons. The talk of pre-emptive attacks creates fears of a cyberarms race and raises the spectre of a war with conventional weapons. With the US most blaming China, Russia and Iran for attacks, that is not what the world wants. Washington needs rules, but it should also spear-head efforts for international protocols and accords.

This article appeared in the South China Morning Post print edition as Cyberwar rules need to be clear